Explore the vast range of titles available.

This study investigates an exceptional Gulf of Mexico dry air outbreak triggered by Hurricane Ian and fueled by dry air originating from drought‐stricken mid‐latitudes under a high‐pressure system. The convergence of meteorological forces, combining cooler, dry air with a warmer, humid sea surface and strong winds, intensified latent and sensible heat exchanges, resulting in significant oceanic heat loss. Data from the 2022 Atlantic hurricane Saildrone mission and satellite flux analysis revealed that the outbreak's total turbulent heat fluxes peaked above 850 Wm−2, comparable to or even surpassing the hurricane’s impact. Argo float measurements recorded a 40‐m deepening of the mixed layer and a 1.4°C temperature decrease. In the tropical Atlantic, wind effects outweighed humidity in driving flux variability. Saildrone’s high‐frequency linewise measurements, distinct from satellite’s footprint averages, provide unique insights into wind variability under high wind conditions. Plain Language Summary Dry air outbreaks in the Gulf of Mexico are meteorological events marked by the influx of drier and often cooler air masses into the typically warm and humid Gulf region. These events occur mostly during the fall and winter months and are associated with atmospheric circulation patterns, particularly the transit of high‐pressure systems from the North American continent. This study highlights an exceptional dry air outbreak in late September 2022, triggered by Hurricane Ian and intensified by dry air originating from drought‐stricken mid‐latitudes, a condition sustained by a persistent high‐pressure system. The interaction between cold, dry air and warm, humid sea surface, coupled with strong winds, intensified the turbulent transfer of heat from the ocean to the atmosphere, resulting in significant ocean heat loss. Data from the 2022 Atlantic hurricane Saildrone mission and satellite flux analysis revealed that the outbreak’s total turbulent heat fluxes peaked above 850 Wm−2, comparable to or even surpassing the hurricane’s impact. Concurrently, the ocean’s surface layer deepened by about 40 m, and the temperature dropped by around 1.4°C. These findings hold substantial implications for understanding the Gulf's weather patterns and their impact on tropical storms, with the potential to influence both their intensity and trajectories. Key Points Hurricane Ian triggered a dry air outbreak, causing substantial turbulent heat loss (>850 Wm−2) and Gulf of Mexico surface cooling (∼1.4°C) Winds, not air‐sea humidity, are a dominant contributor to turbulent heat flux in the tropical Atlantic warm water pool Saildrone’s high‐frequency linewise data, differing from satellite’s footprint averages, offer unique insight into high wind variability

The dry air intrusion over India during summer monsoon break phases is well known. It has been argued that this dry air originates over the desert regions of West Asia. Here, we show that a reservoir of saturation deficit air exists over the western and northern Arabian Sea during the summer monsoon season. The monsoon low-level jet (LLJ) that transports the moisture to continental India in the active phase of monsoon, transports the dry air to northern and central India during the break phase. The LLJ undergoes a weakening and broadening before the monsoon break phase in response to increased barotropic instability. The broadening of LLJ leads to an intensification of zonal flow in the poleward flanks and a weakening at the core. The development of a positive meridional SST gradient over the northern Arabian Sea favours an increase in the low-level zonal flow in the north, which advects the moist deficit air across northwest India. The dry air intrusion results in enhanced static stability over northern and central India and strong suppression of convection. Further, the enhanced static stability weakens zonal flow from the northern Arabian Sea region and leads to the demise of the dry air intrusion. Thus, internal mechanisms are responsible for the dry air intrusion over India and its termination during the break phase of the summer monsoon. An index for the dry air intrusion is constructed based on the saturation deficit transport. This dry air intrusion index is used to identify the dry air intrusion events during monsoon breaks during the 1981–2014 period. The statistics show that there were 34 (4) monsoon breaks with (without) dry air intrusion during 1981–2014 period. We also note that the dry air intrusion and the monsoon breaks are happening simultaneously, suggesting that it is difficult to establish a cause-effect relationship.

Perceived dry air is a common complaint in indoor environments, yet its health associations and environmental factors related to this perception are unclear. We surveyed 7865 families and measured the indoor environment in 399 dwellings in Tianjin, China, from 2013 to 2016. It was found that 10% of the surveyed families reported frequently perceived dry air. The dry air perception was significantly associated with wheeze (adjusted odds ratio (AOR) = 2.60), rhinitis (AOR = 1.91), eczema (AOR = 1.89), and common cold infections (AOR = 1.64) in children and sick building syndrome symptoms in adults (AOR: 2.63–8.59). Higher concentrations of di-isobutyl (DiBP) and benzyl butyl phthalate (BBzP) were observed in homes with dry air perception. Although higher relative humidity might reduce the perception of dry air (AOR = 0.66), lower air exchange rates attenuated the protective effect. Additionally, building characteristics related to pollution exposures, such as living near highways (AOR = 1.31), visible mold spots (AOR = 1.50), and suspected moisture problems (AOR = 1.88), were associated with indoor dry air perception. Our findings suggest that perceived dry air was correlated with indoor exposure to pollution and could be used as an indicator for sick buildings.

The humidity used in the painting process greatly determines the result of painting the car body. This study aims to develop a dry air compressor that can be used to overcome car paint defects. This system consists of a 2 HP compressor engine for sucking air from the atmosphere, two air collection tubes where the first tube contains air obtained from the atmosphere and the second tube contains dry air obtained from the first tube. The inside of the first tube is given a copper coil measuring 5 mm in diameter which is connected to a 120-watt cooler while the second tube is not given a copper coil. Each tube has a diameter of 50 cm and a height of 100 cm. The addition of copper coil aims to separate air from water by means of the condensation process which is the development of this study. Testing of compressor performance is done by turning on the compressor with the exhaust valve closed. After 60 minutes, the air pressure in each tube increased from 0 Psi to 89 Psi, the humidity decreased from 52 % to 38 %, and the temperature decreased from 31.6 °C to 18.2 °C. To see the effect of cooling on the air, the exhaust valves on both tubes were opened. In the first tube there is water coming out, as much as approximately 100 ml while in the second tube there is no water coming out. The water that comes out of the first tube is caused by the condensation process that separates the air from the water and due to the influence of gravity the water falls to the bottom of the tube. The dry air contained at the top of the first tube is flowed into the second tube and is ready to be used for painting the car body. The painting results show that there are no more small holes or paint defects on the paint surface

Carbon dioxide (CO2) is a significant atmospheric greenhouse gas and its concentrations can be observed by in situ surface stations, aircraft flights and satellite sensors. This paper investigated the ability of the CO2 satellite observations to monitor, analyze and predict the horizontal and vertical distribution of atmospheric CO2 concentration at global scales. CO2 observations retrieved by an Atmospheric Infrared Sounder (AIRS) were inter-compared with the Global Atmosphere Watch Program (GAW) and HIAPER Pole-to-Pole Observations (HIPPOs), with reference to the measurements obtained using high-resolution ground-based Fourier Transform Spectrometers (FTS) in the Total Carbon Column Observing Network (TCCON) from near-surface level to the mid-to-high troposphere. After vertically integrating the AIRS-retrieved values with the column averaging kernels of TCCON measurements, the AIRS observations are spatio-temporally compared with HIPPO-integrated profiles in the mid-to-high troposphere. Five selected GAW stations are used for comparisons with TCCON sites near the surface of the Earth. The results of AIRS, TCCON (5–6 km), GAW and TCCON (1 km) CO2 measurements from 2007 to 2013 are compared, analyzed and discussed at their respective altitudes. The outcomes indicate that the difference of about 3.0 ppmv between AIRS and GAW or other highly accurate in situ surface measurements is mainly due to the different vertical altitudes, rather than the errors in the AIRS. The study reported here also explores the potential of AIRS satellite observations for analyzing the spatial distribution and seasonal variation of CO2 concentration at global scales.

Tropical cyclogenesis and rapid weakening are subjects of considerable interest in the literature. This paper addresses the genesis and rapid weakening of a North Indian Ocean tropical cyclone Lehar (November 23–28, 2013). High-resolution analysis has been created by assimilating GPSRO observations using WRF and 3DVAR assimilation techniques. The parent disturbance of tropical cyclone Lehar is traced back using a moisture variable, and it is found to be originating from a westward-moving disturbance. The pathway of genesis is found to be bottom-up, with the vorticity developing from below. Tropical cyclone Lehar weakened from a Category 1 cyclone on November 26, 2013. We analyzed the prospects that contributed to the abrupt drop of tropical cyclone Lehar’s intensity in view of this. The analysis shows dust in the post-genesis (rapid weakening) environment of tropical cyclone Lehar. The analysis of total precipitable water in the post-genesis environment shows that the environment is very dry (< 45 kgm−2), and the spiral bands started disappearing under the influence of dry air intrusion. It has been found that the tropical cyclone Lehar is interacting with the dry air coming from the northern part of the Indian region during the post-genesis (rapid weakening) evolution, and the cyclone started weakening rapidly. The dry air advection from the north of the storm is a primary contributor to the weakening and high deep layer shear in the weakening environment.

In order to upsurge the maneuverability of micro aerial vehicles, a tubercle leading edge inspired by the whale flipper was applied as a passive stall control method. Although this method could be useful to control stall phenomena, the effect of geometrical properties on the flow physic should be investigated to reach the root of them. According to preceding research, the effect of some parameters on the tubercle leading edge wing is a hot topic among researchers. The aim of this research is to explore the effects of sectional wing geometries like amplitude, wavelength, thickness, maximum thickness location, and camber on the aerodynamic feature of full-span tubercle leading edge wing, particularly at 22 degree in post-stall circumstances. The results present that by reducing the amplitude about 2.5%c, the lift coefficient upsurges by about 3.5%; instead, the drag coefficient reduces about 6%. On the other hand, by decreasing the wavelength from 46.2%c to 11.7%c, the drag coefficient and the lift coefficient decrease by about 15% and 19%, respectively. Furthermore, as the thickness rises from 10.55%c to 18.14%c, the lift and drag coefficient goes down about 9.4% and 2.9%, respectively. Furthermore, by increasing the camber from 2.56%c to 3.34%c, the lift to drag ratio goes down by about 1.06%. Finally, by raising the last design variable (maximum thickness location) from 0.26c to 0.51c, the lift to drag ratio increases about 13.7%.

The impact of mid- and upper-level dry air, represented by low relative humidity (RH) values, on the genesis of tropical cyclone (TC) Durian (2001) in the South China Sea was investigated by a series of numerical experiments using the Weather Research and Forecasting model. The mid-level RH was lowered in different regions relative to TC Durian (2001)’s genesis location. Results suggest that the location of dry air was important to Durian (2001)’s genesis and intensification. The rapid development of the TC was accompanied by sustained near-saturated mid- and upper-level air, whereas low humidity decelerated its development. Water vapor budget analysis showed that moisture at mid and upper levels was mainly supplied by the vertical convergence of moisture flux and the divergence terms, and consumed by the condensation process. The horizontal convergence of moisture flux term supplied moisture in the air moistening process but consumed moisture in the air drying process. With a dryer mid- and upper-level environment, convective and stratiform precipitation were both inhibited. The upward mass fluxes and the diabatic heating rates associated with these two precipitation types were also suppressed. Generally, convection played the dominant role, since the impact of the stratiform process on vertical mass transportation and diabatic heating was much weaker. The vorticity budget showed that the negative vorticity convergence term, which was closely related to the inhibited convection, caused the vorticity to decrease above the lower troposphere in a dryer environment. The negative vorticity tendency is suggested to slow down the vertical coherence and the development rate of TCs.

Boundary profile evaluation (BPV) is an approach proposed in order to estimate water vapor content in the atmosphere. It exploits radio occultation (RO) observations of the signals emitted by the satellites of global navigation systems (GNSS) which are eclipsing (rising) as viewed by a low earth orbit satellite (LEO). BPV requires, as a preliminary step, the estimation of the dry background atmosphere model of refractivity (i.e., obtained from bending angle profiles) to be subtracted from the real observations in order to extract water vapor profiles. The determination of the lowest layer of the atmosphere over which the concentration of water vapor can be deemed negligible is particularly crucial for a correct application of the BPV method. In this study, we have applied three methods to set the starting altitudes for the dry air layers of the atmosphere: (1) by air temperature below some threshold values (for example, 250 K); (2) by “smooth” bending angle profiles in ROs; (3) by saturated water vapor pressure. These methods were tested with thermodynamic and bending angle profiles from 912 radiosonde excursions colocated with RO observations. For every dry air starting altitude we determined the best estimator from each of the three methods. In particular, by comparing those estimators with the quantiles and momenta of the dry air starting altitude distributions, we achieved improvements of up to 50% of the humidity profiles.

At Anhembi Morumbi University in Sāo Paulo, Brazil, computational biologist Osmar Pinto Neto and colleagues ran more than 250,000 mathematical models of social-distancing strategies described as constant, intermittent or 'stepping-down' - with restrictions reduced in stages - alongside behavioural interventions such as mask-wearing and hand washing. A June preprint1 from a Massachusetts Institute of Technology (MIT) team in Cambridge analysing COVID-19 testing data from 84 countries suggests that global infections were 12 times higher and deaths 50% higher than officially reported. Many human respiratory viruses - influenza, other human coronaviruses and respiratory syncytial virus (RSV) - follow seasonal oscillations that lead to winter outbreaks, so it is likely that SARS-CoV-2 will follow suit. Evidence suggests that dry winter air improves the stability and transmission of respiratory viruses8, and respiratory-tract immune defence might be impaired by inhaling dry air, she adds.